The applicant will conduct research projects of three types: a. clinical trials to assess the efficacy of promising psychosocial interventions, b. projects to improve methods of classifying substance abusers with the particular aim of defining clinically meaningful subgroups and c. family/genetic studies assessing rates and patterns of substance use disorders and psychopathology in the relatives of substance abusers. The Research Plan provides a detailed description of a project aimed at a promising area in the diagnosis of drug abusers: psychiatric comorbidity, specifically DSM-III-R/DSM-IV Axis II (Personality) disorders. In this renewal study we will 1. Extend data analyses from the first study period, particularly in the areas of characterizing drug use severity and screening for drug abuse, 2. Give a comprehensive battery of assessments to determine rates of Personality Disorders and their clinical correlates in a. a variety of clinical samples of substance abusers and b. demographically matched community controls, 3. Assess several aspects of reliability and validity of differing systems and methods for diagnosing Personality Disorders/Dimensions in substance abusers, 4. Apply and evaluate methods to enhance the reliability and validity of existing instruments for diagnosing Personality Disorders/Dimensions in substance abusers, and 5. Evaluate the associations among different Personality Disorders in substance abusers and seek underlying dimensions of personality pathology in this special population.